@article{article_1727043, title={Synthesis, X-ray Crystallography, Hirshfeld Surface, FT-IR, UV-Vis and DFT Studies of 2,6-Diaminopyridinium Saccharinate}, journal={Erzincan University Journal of Science and Technology}, volume={18}, pages={963–980}, year={2025}, author={Güney, Serkan}, keywords={FT-IR, UV-Vis, Crystal structure, Hirshfeld surface analysis}, abstract={In this study, Density Functional Theory (DFT) was employed to explore the molecular geometry, vibrational behavior (FT-IR, UV-Vis spectra), and electronic features (HOMO–LUMO energy levels) of 2,6-diaminopyridinium saccharinate (HDAPYSAC). Computational studies were performed using the B3LYP exchange–correlation functional in conjunction with the 6–311G(d,p) basis set. Structural data obtained from single-crystal X-ray diffraction confirmed that HDAPYSAC, consisting of saccharinate and diaminopyridinium moieties, crystallizes in the orthorhombic crystal system and belongs to the Fdd2 space group. To further investigate the nature of intermolecular interactions and electron density distribution, Hirshfeld surface mapping and two-dimensional fingerprint plot analyses were carried out. The most significant intermolecular contacts were H···H (32.5%), H···O/O···H (31.7%), H···C/C···H (16.5%), H···N/N···H (7.4%), C···C (5.5%), C···O/O···C (3.0%), and C···N/N···C (2.6%). The calculated HOMO–LUMO energy gap of 3.5661 eV indicates a stable molecular structure. UV–Visible spectroscopy revealed six distinct absorption bands at 276.33, 211.26, 200.10, 173.21, 164.35, and 163.62 nm, corresponding to indirect and direct transition energies of 36188, 47335, 49975, 57733, 60846, and 61117 cm⁻¹, respectively.}, number={3}, publisher={Erzincan Binali Yildirim University}